The mention of "E.M." with no explanation suggested E.M. Forster, so I went off looking for a cartoon I saw in a gay magazine many years ago, which gave an anatomical diagram of the exact route followed by the sensation of being touched on the bum that leads to Maurice's brain and changes his life in Forster's eponymous book, but I didn't find it and instead followed a Google link to a 17th century engraving of someone kissing an arse as penance, but the image in question turned out to be way inside a rather large site mainly about the history of science, https://whewellsghost.wordpress.com, as a result of which I now know about the word "snollygoster". I hope that helps.